Baking oven for producing thin-walled shaped products with baking forms each consisting of two form halves which open and close

ABSTRACT

A baking oven has a multiplicity of baking sheet units stacked one above the other and added to below, after bakable mass has been deposited on a lower most member of the stack, so that the individual molds formed by each upper and lower sheet are closed and held closed by the weight of the sheets above it. The sheets are separated at the top of the stack and recycled to the bottom to receive a new portion of the bakable material.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a national stage of PCT/AT98/00121 filed May 11, 1998 and basedupon Austrian national application A789/97 of May 9, 1997 under theInternational Convention.

FIELD OF THE INVENTION

The invention relates to baking ovens through which baking moldsconsisting of two opening and closing mold halves are transported andinto which, the open state pre-products are placed, which in the closedbaking molds are transformed into thin-walled shaped products, whoseconfiguration corresponds to the hollow space defined by a closed bakingmold.

As pre-products shapeless masses can be used, which harden in the closedbaking molds, or shapeless masses which in the closed baking molds arebaked into thin-walled shaped products. As shapeless baking masses forhuman consumption certain doughs can be used, for instance sugar-less orsugar-containing wafer doughs, which according to the dough recipe, arebaked into crisp, crunchy wafers or to soft wafers, or other bakingdoughs used in the production of sweetened or non-sweetened bakeryproducts. As shapeless baking masses it is also possible to usestarch-based baking masses not suited for human consumption, which arebaked into the form of decayable packaging trays or of other decayablestarch-containing packaging products.

As pre-products it is also possible to use preshaped bodies to beintegrated in the thin-walled shaped products to be produced, which areintroduced in the molds together with the shapeless mass, or preshapedbodies which assume a different configuration in the closed molds. Thepreshaped bodies can be themselves thin-walled shaped products whichwere made from shapeless masses.

BACKGROUND OF THE INVENTION

In the known longitudinally arranged baking ovens for the production ofthin-walled shaped bodies from shapeless masses, for the production ofshaped bodies opening and closing mold halves are contained in 18 to 140opening and closing baking tongs, whereby each mold with both its moldhalves is received in the two tong halves of a baking tongs. The bakingtongs are connected in an endless chain, which runs continuously throughthe antechamber and subsequent baking space of the respective bakingoven in one direction. When passing through the antechamber, the bakingtongs are opened to open of their baking molds, first in order to removethe respective thin-walled shaped body from the open baking mold, andthen to introduce a measured amount of the shapeless mass into theopened baking mold. Subsequently the baking tongs are closed to closeits baking mold. During the subsequent passage through the oven, thebaking molds are heated and each shapeless mass enclosed in the closedbaking molds is baked into a thin-walled shaped body, while the bakingmolds are kept closed against the inner pressure generated inside themduring baking.

In these baking ovens the longitudinally extending endless baking tongchain is arranged in two superimposed transport levels through therespective longitudinally extending baking space, and is guided from theone transport level to the other transport level at the rear end of thebaking space and at the front end of the antechamber frontally connectedto the baking space.

Each baking tong is designed as an externally actuatable machine, bymeans of which the therein contained baking mold is transported throughthe baking oven, opened and closed and kept closed. When passing throughthe antechamber, the baking mold is opened by means of its baking tongs,kept open for a short time and then closed again. When passing throughthe baking space, the closed baking mold is kept closed by means of itsbaking tong. The endless baking tong chain is driven by a driving motor,which produces a continuous revolving motion of the baking tong chain.Because of this continuouse motion each baking tong is subjected to thesame motion sequence. When in the antechamber they pass the respectivelyassigned control mechanisms, stationarily arranged in the antechamber,which in connection with the revolving motion of the baking tong chainproduce each time the respective motion sequence of the baking tongs, orof its parts.

When running though the antechamber the open baking tongs pass theproduct removal station, wherein the baked shaped bodies are removedfrom the opened baking molds and are discharged from the antechamber viathe discharge station of the oven. After the product removal station,the opened baking tongs pass the loading station, wherein the measuredamount portions of the shapeless mass are introduced into the empty,open baking molds. During its travel through the longitudinallyextending, horizontal baking space of the oven, the closed molds areheated in the closed baking tongs. In a gas-heated oven the baking moldsare heated from the outside with hot gases, which are generated in thebaking space of the oven and directed towards the baking tongs. In anelectrically heated oven the baking molds are heated by means of theelectric heating elements built into the tong halves of the bakingtongs, which during their travel through the baking space are suppliedwith electric energy from an external source.

The thin-walled shaped bodies are produced in successive cycles, in thebaking molds transported in cycle through the baking space by the bakingtongs. Each baking cycle takes place in the respective baking moldduring its travel from the loading station through the baking space tothe product removal station. In each single baking cycle, in the loadingstation a shapeless mass is introduced into the baking mold previouslyopened by its baking tongs, the baking mold is closed and kept closed bymeans of its baking tongs, until it is opened again by means of itsbaking tong before it reaches the product removal station, and thethin-walled shaped body is removed from the open baking mold.

When the open baking mold is again transported by its baking tongs tothe loading station, then in this baking mold starts the next bakingcycle for the production of a thin-walled shaped body.

In each baking cycle, during the baking process in the mold kept closedfrom the outside by the baking tongs, the shapeless mass enclosed in theclosed baking mold is distributed, foamed up and baked under pressureinto a foamed, thin-walled shaped body. The outer configuration of theresulting thin-walled shaped body is determined on its upper side by thesurface configuration of the baking surface of the upper mold half andon its underside by the surface configuration of the baking surface ofthe lower mold half of the baking mold. The wall thickness of theresulting thin-walled shaped body is determined by the distance betweenthese two mutually facing baking surfaces, when the mold is closed. Thecontour of the outer border of the resulting thin-walled shaped body isdetermined by the lateral limits of the hollow mold space of the closedbaking mold.

When the baking mold and the baking tong are closed, the two tong halvesand the two mold halves lie opposite to each other. The tong halves aresupported against each other by means of assigned mutually oppositestops. The baking surfaces arranged on the frontal side of the bakingmolds are faced each other and are opposite to each other at apredetermined distance. These two substantially horizontally arrangedbaking surfaces define between them the hollow mold space of the closedbaking mold which, depending on the product to be made in the bakingmold into a thin-walled shaped body, is laterally open, or laterallylimited all around by sealing strips, but not closed up to be gastight.In this hollow mold space a measured amount of the shapeless mass isbaked under pressure into a thin-walled shaped body. The baking gasesformed during baking in the hollow mold space cause the foaming of theshapeless mass, distribute it throughout the hollow mold space and flowout laterally from the hollow mold space of the closed baking mold,between the two baking surfaces, into the baking space of the respectivebaking oven. When the baking mold and the baking tong are closed, thebaking gases create an inner pressure in the hollow mold space of thebaking mold, which is transmitted via the baking surfaces to the moldhalves and from these to the tong halves of the baking tongs. This innerpressure is counteracted by the closed baking tongs, which during theirrevolution, depending on the baking tong and the baking mold, are keptclosed either by the inherent weight of their tong halves, or bystationary closing means acting from the outside, or due to baking tonglocks laterally mounted on their tong halves, thereby preventing theirtong halves lying against each other with their stops from being movedapart by the baking gases.

The inner pressure produced by the baking gases increases in the initialphase of the baking process due to the very intense gas development anddecreases with the progressive escape of the baking gases from thehollow mold space. The thereby occurring pressure maximum of the innerpressure depends mainly on the design of the lateral limitation of thehollow mold space, and is therefore considerably lower in a hollow moldspace which is completely open laterally than in a hollow mold spacewhich is bordered all around by sealing strips and wherefrom the gasescan leave only through a few steam slots of the sealing strips.

In the case of a baking tong whose articulately joined tong halvescontain a baking mold which in the closed state defines a laterally openhollow mold space, wherein the inner pressure increases only slightlyduring baking, the baking mold is kept closed by the inherent weight ofthe respective tong half lying over the hollow mold space, or by astationary closing mechanism, which prevents the tong halves of a bakingtongs passing by from being moved apart.

Baking tongs whose tong halves contain the mold halves of baking moldswhich in the closed state define a hollow mold space which is laterallylimited all around by sealing strips, wherein the inner pressureincreases strongly during baking, are kept closed laterally on twoopposite sides of the respective baking tong. In the case of tong halveslinked by an articulation, on the side of the baking tong opposite tothe articulation a baking tong lock is provided, which is securelylocked when the baking tongs is closed. In baking tongs withoutarticulations, whose tong halves are rectilinearly moved towards andaway from each other for opening and closing the baking mold, on each oftwo opposite sides of the baking tong a baking tong lock is provided,which is securely locked when the baking tongs is closed. Each bakingtong lock is a mechanism built into the respective baking tong, which isexternally actuated when the baking tongs is closed, which in the lockedstate rigidly connects the two tong halves. Each baking tong lock has tobe actuated after the closing of the baking tong and prior to theopening of the baking tongs.

In the known baking ovens, in the baking tongs, respectively in theirbaking tong halves, flat baking plates are integrated, which are formedon the frontal side as upper or lower mold halves of the baking moldsand are heated on their rear side.

From the point of view of construction, layout and function, from theloading station via the individual baking molds and the revolving bakingtongs containing the same, to the stationary control mechanisms causingthe motions of the individual parts of the revolving baking tongs and tothe discharge station for the thin-walled shaped bodies, the knownlongitudinally extending baking ovens with their continuously revolvingbaking tong chains are specifically set up exclusively for theproduction of thin-walled shaped bodies having a single predeterminedconfiguration from shapeless masses prepared according to a certainrecipe.

Such baking ovens are used for the industrial production of ediblewafers, which are baked in the revolving baking molds of the bakingtongs from fluid wafer doughs, which consist primarily of wheat flourand water. Depending on the baking oven and the wafer dough, theconsistency of the produced wafers can be crisp, crunchy and brittlewafers, with a moisture content of maximum 1%-4%, or they can have theconsistency of soft, elastic wafers with a moisture content of 8% ormore.

Such baking ovens are also used for the industrial production of flatdecomposable packaging trays, which are baked in the revolving bakingmolds of the baking tongs from pourable starch-based shapeless massesand which have an elastic consistency with a moisture content of 6% to22%.

The known longitudinally extending baking ovens with their endlessbaking tong chains comprising 18 to 140 baking tongs are mechanicallyvery cumbersome machines. The baking molds are received in the bakingtongs composed of several components and run through the baking space onlateral running wheels in lateral guide rails on both transport levelsof the baking oven. In the antechamber along the guide path of thebaking tongs, control cams and mechanisms produce the motions of thetong halves for the opening and closing of the baking molds and themotions of the locking elements of the baking tong locks for locking andunlocking of the closed baking tong. Mechanically cumbersome is also theendless baking tong chain, for which a pneumatic or hydraulicchain-tensioning device mounted on the oven frame is required, and whichin addition to the baking tongs also consist of two lateral transportchains, which interconnect the baking tongs and run over chain guidesarranged at both ends of the baking oven.

In the known longitudinally extending baking ovens for the production ofthin-walled shaped bodies the difference in the production capacity ofthin-walled shaped bodies determined by the number of its baking tongs,or baking molds, shows up only in the differences in the length of thebaking ovens or their baking spaces. When an existing longitudinallyextending wafer baking oven has to be replaced by a new longitudinallyextending baking oven with a higher capacity, then at the site of thebaking oven a longer construction space is required for the new bakingoven. Under limited space conditions, the length available at the sitebecomes very quickly a limiting factor for any further capacity increaseof the longitudinally extending baking oven and the productioninstallations connected thereto for the further treatment and processingof the thin-walled shaped bodies up to the packaging machine for the endproduct produced from the thin-walled shaped bodies, which is providedat the end of the respective production installation.

From German Patent 714 019 a wafer baking machine is known wherein wafermolded boxes are guided in the side walls of the machine by lateralrunning rollers. The wafer mold boxes at their top and bottom sides havedepressions corresponding to the pattern of the upper or lower side ofthe wafer to be produced, each carrying lateral hook catches projectingdownwards beyond the lower side and thereto assigned locking pins closeto their upper side. In a lower transport level, these molding boxes arefilled with a baking mass at their upper side and continuously assembledinto baking molds at the lower end of a molding box stack supported onstationary catches and extending through a vertical baking shaft upwardsto an upper removal station for the baked wafers, each of themconsisting of two superimposed molding boxes, rigidly connected by meansof the hook catches of the upper box fastened to the locking pins of thelower box. At the lower end of the baking shaft each time a molding boxfilled with baking mass at its upper side is pressed from below into thebaking shaft by means of a crank of a connecting rod gear and joinedtogether with the lowest molding box of the molding box stack to form abaking mold. Thereby the entire molding box stack is lifted by thestationary catches, and lifted by one molding box height, whereby thehook catches of the lowermost molding box in the stack lock into thelocking pins of the newly arrived molding box, and then the entire stackwith its newest lowermost molding box is again deposited on thestationary catches. With each addition of a molding box at the lower endof the stack, the baking molds in the stack travel stepwise upwardsthrough the baking shaft, while wafers are baked in the baking moldsformed by them. When the stack is lifted, in the uppermost baking moldof the stack the hook catches of the upper molding box are swung awayfrom the locking pins of the underlying molding box and the uppermostmolding box is coupled to the two endless link chains of an endlessconveyor running in the side walls of the machine frame, which liftsthis molding box by releasing the uppermost baking mold from the moldingbox stack and transports it through an upper transport level and a rearvertical transport stretch into the lower transport level, back to thelower end of the baking shaft, where this molding box is again uncoupledfrom the link chain of the endless conveyor. When the uppermost moldingbox is lifted from the stack, the baked wafer is left lying on the upperside of the underlying molding box and is removed from this molding boxin the upper removal station by means of a stripper. This wafer bakingmachine has short baking shaft with a low molding box stack, whichconsists of a few, relatively thin-walled molding boxes, which arerigidly interconnected by means of hook catches and locking pins, inorder to be able to withstand the high inner pressures occurring duringthe baking of the wafers in the baking molds formed by the moldingboxes.

OBJECT OF THE INVENTION

It is the object of the invention to provide a compact baking oven forthe production of thin-walled shaped bodies in baking molds, eachconsisting of two mold halves which can be opened and closed.

SUMMARY OF THE INVENTION

According to the invention, a baking oven for the production ofthin-walled shaped bodies in baking molds comprises of two mold halveswhich can be opened and closed, which define with their mold halves theouter configuration of the shaped bodies produced therein. In thisbaking oven stackable baking sheets units passing through a closed cycleare provided, which on their top side carry the bottom mold halves ofthe baking mold and on their bottom side carry the top mold half of thebaking molds and which lying on top of each other in pairs form closedbaking molds. In a bottom loading station, each baking sheet unit isloaded at its upper side with the pre-product and then integrated in avertical stack consisting of baking sheet units resting on a bottomsupport device and which extends upwards through a vertical baking shaftto a top removal station for the baked shaped bodies. At its upper endthe stack is constantly dismantled into separate baking sheet units andis constantly replenished at the bottom by a stacking device due to thecontinuous addition of baking sheet units loaded with the pre-product,so that the baking molds formed by the baking sheet units travel upwardsand stepwise through the baking shaft, while the pre-products containedin the baking molds are baked into thin-walled shaped bodies. Accordingto the invention the baking sheet units are only loosely stacked on topof each other, and each individual baking mold formed by twosuperimposed baking sheet units is kept closed against the innerpressure generated during baking only by the weight of the respectivestack part resting thereon, while within the stack it travels upwards insteps through the vertical baking shaft, to the top removal station.

The construction of the invention allows for a clear reduction of thenumber of parts of the baking oven which have to be constantly moved, bysubstituting the transport device extending along the baking shaft withthe constantly replenished baking mold stack, which is constantlyrenewed or dismantled outside the baking shaft. The constantly renewedbaking mold stack, which is kept together by its own weight requiresclearly less maintenance than a transport device for the closed bakingmolds extending along the baking shaft, or the endless baking mold chainof a known longitudinally extending baking oven, which in its bakingtongs contains the baking molds and which continuously revolves with allits movable parts in the horizontal hot baking space of the baking oven.

The construction of the baking oven according to the invention can dowithout the lateral locking devices required in the known baking ovensfor the connection of the two mold parts and without the lateral runningwheels required in the known baking oven for guiding the baking sheetunits within the baking oven. In the construction of the baking ovenaccording to the invention the constantly replenished stack of stackablebaking sheet units which can be used on both sides, moving through thevertical baking shaft, has no mobile parts which are transported throughthe baking shaft and which require expensive materials and complicatedconstructions due to the high temperatures in the baking shaft.

According to a further feature of the invention, above the baking shafta separating device can be provided, which removes the baking sheetunits one after the other from the top of the stack, for the purpose ofdismantling the stack and opening the baking molds.

According to a further feature of the invention, outside the bakingshaft, a separate vertical conveyor running in the opposite directioncan be provided for the return transport of the baking sheet units tothe bottom loading station.

According to a further feature of the invention, the baking sheet unitscan each be provided with mutually corresponding upper, respectivelylower stacking surfaces, by means of which they lie loosely on top ofeach other within the stack.

According to a further feature of the invention, on the top side of abaking sheet unit several baking mold parts designed as lower bakingmold halves can be arranged next to each other, and on the bottom sideof a baking sheet unit several baking mold parts designed as upper moldhalves can be arranged next to each other.

According to a further feature of the invention, the upper stackingsurfaces of the baking sheet units assigned to the top side can be eachintegrated in the sealing strips of the lower baking mold halvesarranged on the top side of the baking sheet unit, whereby the bakingsheet units lie loosely on top of each other with the sealing strips oftheir baking mold halves within the stack formed by them.

The stackable baking sheet units which can be used on both sides withthe baking mold halves arranged on their top side or bottom side, allowfor a twisting and bending resistant construction of the sheet bodywhich supports the back of the baking surfaces, whereby the heatingchannels built into the sheet body further reinforce the sheet body. Themutually facing stacking surfaces allow for a precise mutual placementof the two mold halves of a baking mold which is formed between twosuperimposed baking sheet units during the closing of the baking mold orwhen the two baking sheet units are placed one on top of the other.

The stackable baking sheet units can be made in one piece, whereby thebaking surfaces and the stacking surfaces arranged on their top andbottom sides can be integrated in the respective sheet body.

The stackable baking sheet units can each consist of a top part formedby the upper baking sheet and a bottom part formed by the lower bakingsheet. The upper baking sheets, together with the lower baking moldhalves formed on their frontal sides, form the top sides of the bakingsheet units, and together with the reinforcement ribs formed on theirback side, they form the upper part of the bordering walls of theheating channels of the baking sheet units. The lower baking sheets,together with the upper baking mold halves formed on their frontalsides, form the bottom sides of the baking sheet units, and togetherwith the reinforcement ribs formed on their back sides form the lowerpart of the border walls of the heating channels of the baking sheetunit. At their back sides, these upper and lower baking sheets lie ontop of each other with the frontal sides of their reinforcement ribs andare rigidly connected with each other in pairs to the respective bakingsheet unit.

These two-sided usable, stackable baking sheet units, which can be madein one piece, or of a parallelepipedic plate body with baking sheetsattached to its top and bottom sides, or of two baking sheets restingagainst each other with their back sides, are stacked on top of eachother for forming baking molds and thereby pushed against each otherfrom below, with their mutually assigned stacking surfaces. Thereby anupper mold half formed on the bottom side of the upper baking sheet unitis put together with a lower mold half formed on the top side of thelower baking sheet unit to form a baking mold and this baking mold isbeing closed at the same time. The closed baking mold limited at the topand the bottom by two superimposed baking sheet units can contain asingle hollow space for the production of thin-walled shaped bodies.This baking mold can also contain several hollow mold spaces of equalsize for the simultaneous production of several thin-walled shapedbodies in a single baking mold. This baking mold can also containseveral hollow mold spaces of various configuration for the simultaneousproduction of several different thin-walled shaped bodies in a singlebaking mold.

In the stack according to the invention, consisting of stackable bakingsheet units which can be used on both sides and which is constantlyreplenished at its bottom end constantly again dismantled at its topend, at the bottom end the baking sheet units are stacked from below oneon top of the other, and at the upper end are separated, whereby in theloading station assigned to the bottom end of the stack a new bakingsheet unit is loaded at its top side with pre-product, before it isintegrated in the next stacking step into the stack resting with itsentire weight on the lowermost baking sheet unit. The new baking sheetunit is moved underneath the stack and pressed against the lowermostbaking sheet unit of the stack, until it bears the entire stack weightas its lowermost baking sheet unit. In this stacking step, the stack isreplenished at its bottom end with a baking sheet unit and at the sametime the upper mold half formed on the bottom side of its lowermostbaking sheet unit is put together with the lower mold half filled withpre-product on the top side of the new baking sheet unit to form a newclosed baking mold. This baking mold is the lowermost baking mold in thebaking mold stack formed by the baking sheet units stacked on top ofeach other. The hollow mold space of this baking mold is kept closeagainst the inner pressure generated during baking by the weight of theentire stack. This baking mold travels upwards together with the twobaking sheet units defining its hollow mold space by one level with eachfurther stacking step, and on each level it is kept closed by the weightof the part of the stack existing above this level. At the top end ofthe stack the hollow mold space of the baking mold is kept closed onlyby the weight of the upwardly limiting baking sheet unit, and when thisbaking sheet unit is lifted at the dismantling of the stack, it is alsoopened. The thin-walled shaped body produced in this hollow mold spaceremains on the top side of the lower baking mold half formed on theuppermost baking sheet unit of the stack and can be removed directlytherefrom.

The two-sided usable, stackable baking sheet units are transportedthrough the respective baking oven in a close cycle and pass through thevertical shaft of the baking oven in a vertical stack, which consists ofstacked baking sheet units lying on top of each other and iscontinuously replenished at its bottom end with one baking sheet unitand continuously reduced by one baking sheet unit at its top end. Thetwo-sided usable, stackable baking sheet units make it possible tocombine the formation process of the respective stack with the closingprocess of the baking molds and to combine the dismantling process ofthe stack with the opening process of the baking molds, so that noadditional mechanisms or actuating devices are required for the bakingsheet units in order to close the baking molds after they are loadedwith pre-product and for the opening of the baking molds prior to theremoval of the baked shaped body. The stacking device of the baking ovenforming the stack stacks the sheets from below one on top of each other,thereby closing the baking molds. The separating device of the bakingoven which dismantles the stack lifts the baking sheet units from therespective stack and thereby opens the baking molds at the same time,respectively separates them into their baking mold halves.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects, features, and advantages will become morereadily apparent from the following description, reference being made tothe accompanying drawing in which:

FIG. 1 schematically in section a baking oven with a vertical transportpath for the production of thin-walled shaped bodies,

FIG. 2 is a cross sectional view showing schematically a segment of thetransport path traversing the vertical baking shaft for the productionof thin-walled shaped bodies,

FIG. 3 is a section of a part of a stackable baking sheet unit for theproduction of thin-walled shaped bodies,

FIG. 4 shows the part of the stackable baking sheet units of FIG. 3 in alongitudinal section,

FIG. 5 shows a segment of a sealing strip of the stackable baking sheetunits of FIG. 3, in a side view,

FIG. 5a is a detail of FIG. 5 in the direction of arrow A;

FIG. 6 is a section of a segment of a vertical stack formed by bakingsheet units stacked on top of each other, wherein the baking sheet unitswithin the stack lie loosely on top of each other and are kept togetheronly by the weight,

FIG. 7 is a top view of a support device for a vertical stack formed bystackable baking sheet units, arranged at the lower end of the verticaltransport path for the production of thin-walled shaped bodies, and

FIG. 8 is a side view of the support device of FIG. 7.

SPECIFIC DESCRIPTION

FIG. 1 shows a gas-heated baking oven 1 for the production ofthin-walled shaped bodies, which for instance are flat rectangularsheets which at their upper and lower sides have wafer patterns formedby raised ribs. These thin-walled shaped bodies are made of a shapelessmass in baking molds which can open and close, each consisting of twomold halves which determine the outer configuration and the wallthickness of the thin-walled shaped body.

For the formation of the baking molds which can open and close,stackable baking sheet units 2 (FIG. 2-5a) which can be used on bothsides are provided. These molds have parallelepipedic plate bodies whichcan be heated through heating channels and are provided on two oppositefrontal sides 2 a (FIG. 4) with lateral holding openings 4, and which onthe top sides 2 b and the bottom sides 2 c (FIG. 3) carry bakingsurfaces 5, 6 and the thereto assigned stacking surfaces 7, 8. The topsides 2 b of the baking sheet units 2 are designed as lower mold halvesof the baking molds, and the bottom sides 2 c of the baking sheet units2 are designed as upper mold halves of the baking molds. Twosuperimposed baking sheet units 2 lie with their mutually facingstacking surfaces 7, 8 on top of each other and form together a closedbaking mold for the respective thin-walled shaped body to be produced.This baking mold consists of the upper baking mold half arranged on thebottom side 2 c of the baking sheet unit 2 and of the lower mold halfarranged on the top side 2 b of the lower baking sheet unit 2. Thestackable baking sheet units 2 which can be used on both sides with therespective therein integrated baking mold halves are set for theproduction of a certain thin-walled shaped body.

Baking sheet units 2 for the production of flat rectangular sheets havebasically a rectangularly shaped plate body. On the top side 2 b and thebottom side 2 c of the plate body a substantially flat, rectangularbaking surface 5, 6 defined by lateral sealing strips 9, 10 is formed.The stacking surfaces 7, 8 of the baking sheet units 2 are integrated inthese sealing strips 9, 10, each of them protruding beyond the bakingsurface 5, 6 they define and together with the same form the upperbaking mold half 5, 9 or the lower baking mold half 6, 10 of the bakingsheet unit 2. In the lower baking mold half 5, 9 at least one steamchannel 11 traversing at least one sealing strip 9 b is formed in twoopposite sealing strips 9 b. Two baking sheet units 2 stacked on top ofeach other lie with the sealing strips 9 and 10 of their mutually facingbaking mold halves 5, 9, respectively 6, 10 on top of each other andform a closed baking mold, which is completely closed except for thelateral steam channels, through which the gases generated during bakingcan escape when the baking mold is closed.

Baking sheet units for the production of round, triangular, pentagonalor fan-shaped flat layers can basically have a plate body with round,triangular, pentagonal, or fan-shaped baking surfaces on their top andbottom sides, each defined by lateral sealing strips wherein thestacking surfaces of the respective baking sheet unit are integrated.However these baking sheet units can also have parallelepipedic platebodies corresponding in shape to the layer to be produced with a round,triangular, pentagonal or fan-shaped base.

Baking sheet units for the production of thin-walled bodies shaped likerectangular trays slightly opening upwards, have basically a rectangularplate body which on the top side carries an upper baking surfaceprovided with a depression corresponding to the configuration of thetray, and on the it bottom side a lower baking surface provided with araised portion corresponding to the configuration of the tray. Bothbaking surfaces are limited by sealing strips which correspond to thecontour of the tray and contain the stacking surfaces of the bakingsheet unit.

Baking sheet units for the production of thin-walled shaped bodies,which are shaped as flat layers with undefined borders have aparallelepipedic plate body on whose top and bottom sides bakingsurfaces corresponding to the respective contour of the flat layers tobe produced are arranged, and outside the same spacers are arrangedwhich determine the wall thickness of the shaped body area provided,wherein the upper, respectively lower stacking surfaces of the bakingsheet unit are integrated.

In the baking oven shown in FIG. 1 the two-sided usable, stackablebaking sheet units 2 are transported through the baking oven 1 in aclosed cycle inside of the outer heat-insulating lining 12 of the bakingoven 1. This cycle comprises a vertically upwards leading transport path13, at the beginning of which the baking sheet units 2 are stacked ontop of each other for the formation of baking molds and at whose end forthe opening of the baking molds the baking sheet units 2 are againseparated. This vertical transport path 13 for the closed baking moldsleads from a lower loading station 14 through a vertical baking shaft 15built as a baking space to an upper removal station 16. From the removalstation 16 the separated baking sheet units 2 are transferred to avertically downwards leading transport path located outside the bakingshaft 15 and there they are lowered individually, before they are againdirected to the vertically upwards leading transport path 13.

The closed baking molds and the baking sheet units 2 forming the sameare transported upwards through the baking shaft 15 by the continuouslyreplenished stack 18, consisting of loosely superimposed baking sheetunits kept together only by the weight.

Inside the baking oven 1, the baking shaft 15 is limited towards theoutside by a heat-insulating shell 19. Inside the baking shaft 15 andalong the stack 18 gas burners 20 are arranged vertically on top of eachother. The heating gases produced by them flow through the heatingchannels 4 of the baking sheet units 2 throughout the stack 18, thusheating the closed baking molds enclosing the pre-products, which arecontained in the stack 18.At the bottom of the baking shaft 15, thestack 18 is continuously replenished with baking sheet units 2 suppliedfrom a lower horizontal conveyor, by means of a stacking device 21 can.The stacking device 21 consist of a support device 23 assigned to thebottom end of the stack 18 and of a lifting device 24 arrangedunderneath the stack. The support device 23 is engaged with thelowermost baking sheet unit 2 of the stack 18, on which rests the weightof the entire stack 18. The support device 23 comprises two carriages25, 26 which are located opposite from each other in a horizontal plane.These carriages 25, 26 are vertically supported in the frame of thebaking oven 1 and are provided at mutually facing frontal sides withholding bolts 27, 28, which reach into the lateral holding openings 4 ofthe lowermost baking sheet unit 2 of the stack 18 and carry the entireweight of the stack 18. During a stacking process the two carriages 25,26 are at first pulled apart for releasing the stack 18 and thereby arepulled out with their holding bolts 27, 28 from the lowermost bakingsheet unit 2 of the stack 18, and then for fastening the stack 18, theyare again pushed together and thereby pushed back with their holdingbolts 27, 28 into the holding openings 4 of the newest lowermost bakingsheet unit 2 of the stack.

The baking sheet units 2 to be stacked are transported by the horizontalconveyor 22 through a loading station 14, which precedes the verticaltransport path 13 and the bottom end of the stack 18. This loadingstation 14 can for instance be built like a pouring station, whereineach time a measured amount of a pre-product prepared as a shapelessmass is poured onto the top side 2 b of the respective baking sheet unit2. The baking sheet units 2 loaded with the pre-product on the top side2 b is transported by the lower horizontal conveyor 22 under the stack18 and there it is lifted from the lower horizontal conveyor 22 by avertically displaceable ram 29 of the lifting device 24. This ram 29presses the new baking sheet unit 2 to be integrated in the stack 18from below against the lowermost baking sheet unit 2 of the stack 18,takes over its entire weight and thereby integrates this baking sheetunit 2 as the new lowermost baking sheet unit 2 in the stack 18. Afterthe heretofore lowermost baking sheet unit 2 of the stack 18 is releasedby the support device 23, the ram 29 of the lifting device 23 lifts theentire stack 18 by the height of one baking sheet unit 2. Subsequentlythe support device 23 is brought into engagement with the new lowermostbaking sheet unit 2 of the stack 18 and the stack 18 is deposited by thelifting device 24 onto the support device 23.

At the top of the baking shaft 15, the stack 18 is continuouslyseparated into individual baking sheet units 2 by a separating device30, which comprises a grip head 32 carried by an upper horizonalconveyor 31, which seizes the uppermost baking sheet unit 2 of the stack18 electromagnetically or mechanically, lifting it from the stack 18 andtransferring it to the vertical conveyor 33 of the vertically downwardleading transport path 17 located outside the baking shaft 15.

When the gripping head 32 lifts the uppermost baking sheet unit 2 fromthe stack 18, the uppermost baking mold, which up to this moment wasupwardly limited by this baking sheet unit 2, opens. The shaped bodybaked in this baking mold is left on the upper side of baking sheetunit, which up to this point limited this baking mold downwards. Theformer is now the uppermost baking sheet unit 2 of the stack 18, whosetop side forms the top side of the stack 18.

The shaped bodies baked in the stack 18 are each removed in the removalstation 16 by means for instance of a suction head (not shown) andguided to a discharge station 34 in the vicinity of the stack 18,through which they are discharged from the baking oven 1.

In the baking shaft 15 traversed by the stack 18 (FIG. 1), the gasburners 20 can be arranged vertically on top of each other on twoopposite sides of the stack 18, alternately staggered with respect toeach. The heating gases flowing from one side of the stack 18 into theheating channels 4 of the baking sheet units 2, after flowing though thebaking sheet unit 2, escape on the opposite side of the stack 18 intothe baking shaft 15. The heating gases leave the baking shaft 15together with the heating gases escaping from the closed baking molds ofthe stack 18 through two upper exit openings 35, 36. The gas burners 20and the thereto assigned exit openings 35, respectively 36 are arrangedon different sides of the stack 18.

According to an alternate embodiment example (FIG. 2) the baking shaft37 can be subdivided by a horizontal dividing wall in two superimposedshaft sections 39, 40, wherein the gas burners 41, 42 and the theretoassigned exit openings 43, 44 can be arranged on the same side of thestack 18, vertically above each other. Each shaft section 39, 40contains a lower heating zone 39 a, respectively 40 a, wherein the gasburners 41, respectively 42 are arranged, and an upper heating zone 39b, respectively 40 b, wherein an exit opening 43, respectively 44 of thebaking shaft 39, respectively 40 is arranged. The gas burners 41,respectively 42 and the exit opening 43, respectively 44 are eachseparated from each other by an intermediate floor 45, respectively 46,which has a central opening 45 a, respectively 46 a for the passage ofthe stack 18 and a lateral floor opening 45, respectively 46 for thepassage of the heating gases and baking gases from the lower heatingzone 39 a, respectively 40 a into the upper heating zone 39 b,respectively 40 b.

The horizonal conveyor 22 arranged beneath the baking shaft 15 extendsbeyond the bottom end of the stack 18 to a discharge station 47 for thestackable baking sheet units 2 in the vicinity of the side wall 12 a ofthe baking oven 1, shown on the right in FIG. 1, which has a servicedoor (not shown) provided in the side wall 12 a of the baking oven 1.

Via the discharge station 47 for the stackable baking sheet units 2, abaking sheet unit 2 which has been transferred by the verticallydownwards leading transport path 17 to the lower horizontal conveyor 22,can be transported by the lower conveyor 22 bypassing the lower end ofthe stack 18 to the discharge station 47 and from there exit the bakingoven 1. After the baking sheet unit 2 has been cleaned and serviced, thesame can be reintroduced in the baking oven 1 via the discharge station47 and transported by the lower horizontal conveyor 22 to the stackingdevice 21, without having to dismount or dismantle parts of the bakingoven 1.

The discharge station 47 for the stackable baking sheet units 2 makespossible the replacement of individual baking sheet units 2 via thedischarge station 47 with other baking sheet units 2, this way refittingthe baking oven 1 for the production of other thin-walled shaped bodies.So for instance stackable baking sheet units 2 provided for theproduction of flat layers can be exchanged for stackable baking sheetunits provided for shallow trays.

The stack 18 forming the transport path 13 leading vertically upwards inthe baking oven 1 consists of superimposed baking sheet units 2 whichare integrated one after the other into the stack 18 due to successivestacking processes of the lower stacking device 21, and after travellingthrough the stack 18 and the baking shaft 15 are again removed from thestack 18 by the separating device 30 at the top end of the stack 18.

With each stacking process one new baking sheet unit 2, which hasalready been loaded with the pre-product on its top side 2 a, isintegrated from underneath into the stack 18. The new baking sheet unit2 is transported by the lower horizontal conveyor 22 under the bottomend of the stack 18 and, by means of the ram 29 of the lifting device 24arranged at the bottom, is lifted from the lower horizontal conveyor 22towards the bottom end of the shaft 18 and pressed with its top side 2 aagainst the bottom side of the stack 18. Subsequently the new bakingsheet unit 2, together with the stack 18 resting thereon, is furtherlifted by the ram 29 of the lifting device 24 and the stack 18 with itheretofore lowermost baking sheet unit 2 is lifted from the horizontalholding bolt of the thereto assigned holding device 23. The holdingbolts are pulled out from the heretofore lowermost baking sheet unit 2of the stack 18 due to the fact that their supporting carriages arepulled apart horizontally. The stack 18 is further lifted by the ram 29of the lifting device 24, until the lateral holding openings of the newand now lowermost baking sheet unit 2 of the stack 18 are directedtowards the horizontal holding bolts of the holding device 23. Now thetwo carriages of the holding device 23 are pushed together and theholding bolts are pushed into the holding openings of the new lowermostbaking sheet unit 2 of the stack 18. Subsequently the ram 29 of thelifting device 24 is lowered to its initial bottom position, whereby itfirst deposits the stack 18 on the holding bolts of the holding device23, before it is lowered alone below the transport level of the lowerhorizontal conveyor 22. Subsequently the lower horizontal conveyortransports the next baking sheet unit 2 which on its top side 2 a hasalready been loaded with the pre-product under the bottom end of thestack 18 and the next stacking process starts.

During each stacking process the already loaded lower baking mold halfformed on the top side 2 a of the baking sheet unit 2 to be integratedis pushed from below with its upwards pointing sealing strips againstthe downwards pointing sealing strips of the baking mold formed on thebottom side 2 b of the lowermost baking sheet unit 2 of the stack 18,and both mold halves form a closed baking mold.

With each stacking process at the bottom end of the stack 18 a newclosed baking mold is formed, whose hollow mold space is defined upwardsand downwards by the mutually facing baking surfaces of the twolowermost baking sheet units 2 of the stack 18, and laterally by thesuperimposed sealing strips of these two baking sheet units. This hollowmold space is completely closed, except for the steam slots provided inthe sealing strips. The shapeless mass enclosed in the hollow mold spacedue to the closing of the baking mold during the stacking process isbaked into thin-walled shaped body formed like a flat layer, while thehollow mold space, together with the baking sheet units 2 delimiting it,travels stepwise upwards in the stack 18 through the baking shaft 15.During this baking process, the shapeless mass is foamed by the bakinggases generated therein and distributed through the hollow mold space,before the baking gases leave the hollow mold space through the steamslots and escape from the closed baking mold into the baking shaft 15.The inner pressure generated during baking inside the hollow mold space,which increases rapidly in the initial phase and after a short timedecreases again rapidly, is counteracted by the weight of the respectivepart of the stack 18 lying on top of the hollow mold space. The hollowmold space travels upwards in the stack 18 by one level with each newstacking process, and the part of the stack 18 lying on top of itbecomes smaller and lighter with each baking sheet unit 2 removed at itstop end. During the entire baking process, the inner pressure generatedin the hollow mold space is always clearly smaller than the pressureexerted from above on the hollow mold space by the weight of the part ofthe stack 18 lying on top of it. This is achieved due to the high weightof the stack 18, which is determined by the weight of the individualbaking sheet units 2 and by the number of the baking sheet units 2stacked on top of each other.

At the top end of the stack 18 the hollow mold space is kept closed onlyby the weight of the baking sheet unit 2 bordering it on the top andwhen this baking sheet unit 2 is lifted while the stack 18 is beingdismantled, it is also opened. For the separation of the baking sheetunits 2 at the top end of the stack 18 the gripper head 32 of the upperhorizontal conveyor 31 is passed over the top end of the stack 18 andkept on standby until the stack 18 is lifted to its uppermost positionduring a stacking process performed by the lifting device 24 arrangedbeneath the stack. Then the gripping head 32 seizes the uppermost bakingsheet unit 2 of the stack 18 and holds it, while the stack 18 is againlowered by the lifting device 24 and the heretofore second to uppermost,and now the uppermost baking sheet unit 2 is removed downwards from thebaking sheet unit 2 held by the gripping head 32. As a result the bakingmold previously formed by the two uppermost baking sheet units 2 of thestack 18 is opened, whereby the baked shaped body is left lying on thetop side of the now uppermost baking sheet unit 2 of the stack 18 and isremoved from there, while the gripping head 32 transports the removedbaking sheet unit 2 to the upper end of the vertical conveyor 33arranged outside the baking shaft 15. The gripping head 32 of the upperhorizontal conveyor 31 is again passed over the top end of the stack 18,before the same is lifted again to its uppermost position by its liftingdevice 24 during its next stacking process and the next separationprocess starts.

What is claimed is:
 1. Baking oven for the production of thin-walledshaped bodies in baking molds defined by the top and bottom sides ofstackable baking sheet units lying loosely on top of each other within acontinuously renewed and dissolved stack supported on a bottom holdingdevice and extending through a vertical baking shaft up to a removalstation for the baked thin-walled shaped bodies, each baking mold beingdefined by two superposed baking sheet units and being kept closed onlyby the weight of the stack portion above it while being moved stepwiseupwards within said stack and through said baking shaft, each bakingsheet unit being loaded with pre-product in a bottom loading station andintegrated into said stack beneath said baking shaft by a stacking unitand removed from said stack above said baking shaft.
 2. The baking ovenof claim 1 further comprising a baking sheet unit separation deviceabove said baking shaft or removing said baking sheet units one afterthe other from the top of said stack and for opening said baking molds.3. The baking oven of claim 1 further comprising a vertical conveyoroutside said baking shaft for conveying said baking sheet units back tosaid bottom loading station.
 4. The baking oven of claim 1, wherein saidbaking sheet units comprise upper and lower stacking surfacescooperating with one another within said stack.
 5. The baking oven ofclaim 1, wherein on the top sides of said baking sheet units severalbaking mold parts designed as lower mold halves are arranged next toeach other and on the bottom sides of said baking sheet units severalbaking mold parts designed as upper mold halves are arranged next toeach other.
 6. The baking oven of claim 1, wherein the top and bottomsides of said baking sheet units define baking mold halves with sealingstrips with integrated stacking surfaces and said baking sheet units lieloosely on top of each other within said stack with the sealing stripsof their baking mold halves.